Why does not work rawprinterhelperclass in persian (farsi)?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;
using System.Drawing.Printing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.IO;
public static class RawPrinterHelper
{
    public static byte[] arabicEncoding(string text)
    {
        Encoding ec = Encoding.GetEncoding(864);
        byte[] memByte = ec.GetBytes(text);
        return memByte;
    }
    // Structure and API declarions:
    [StructLayout(LayoutKind.Sequential,CharSet = CharSet.Unicode )]
    public class DOCINFOA
    {
        [MarshalAs(UnmanagedType.LPStr, SizeConst = 4)]
        public string pDocName;
        [MarshalAs(UnmanagedType.LPStr, SizeConst = 4)]
        public string pOutputFile;
        [MarshalAs(UnmanagedType.LPStr, SizeConst = 4)]
        public string pDataType;
    }

    [DllImport("NativeLib.dll", EntryPoint = "pinvoke_name", SetLastError = true, CharSet = CharSet.Unicode, CallingConvention = CallingConvention.StdCall)]
    private static extern void pinvoke_name_ptr(byte[] data);

    [DllImport("winspool.Drv", EntryPoint = "OpenPrinterA", SetLastError = true,CharSet = CharSet.Unicode , CallingConvention = CallingConvention.StdCall)]
    public static extern bool OpenPrinter([MarshalAs(UnmanagedType.LPStr)] string szPrinter, out IntPtr hPrinter, IntPtr pd);

    [DllImport("winspool.Drv", EntryPoint = "ClosePrinter", SetLastError = true, CharSet = CharSet.Unicode, CallingConvention = CallingConvention.StdCall)]
    public static extern bool ClosePrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "StartDocPrinterA", SetLastError = true, CharSet = CharSet.Unicode, CallingConvention = CallingConvention.StdCall)]
    public static extern bool StartDocPrinter(IntPtr hPrinter,  Int32 level, [In, MarshalAs(UnmanagedType.LPStruct)] DOCINFOA di);

    [DllImport("winspool.Drv", EntryPoint = "EndDocPrinter", SetLastError = true, CharSet = CharSet.Unicode, CallingConvention = CallingConvention.StdCall)]
    public static extern bool EndDocPrinter(IntPtr hPrinter );

    [DllImport("winspool.Drv", EntryPoint = "StartPagePrinter", SetLastError = true, CharSet = CharSet.Unicode, CallingConvention = CallingConvention.StdCall)]
    public static extern bool StartPagePrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "EndPagePrinter", SetLastError = true, CharSet = CharSet.Unicode, CallingConvention = CallingConvention.StdCall)]
    public static extern bool EndPagePrinter(IntPtr hPrinter);

    [DllImport("winspool.Drv", EntryPoint = "WritePrinter", SetLastError = true, CharSet = CharSet.Unicode, CallingConvention = CallingConvention.StdCall)]
    public static extern bool WritePrinter(IntPtr hPrinter, IntPtr pBytes, Int32 dwCount, out Int32 dwWritten);

    // SendBytesToPrinter()
    // When the function is given a printer name and an unmanaged array
    // of bytes, the function sends those bytes to the print queue.
    // Returns true on success, false on failure.
    public static bool SendBytesToPrinter( string szPrinterName, IntPtr pBytes, Int32 dwCount)
    {
        Int32    dwError = 0, dwWritten = 0;
        IntPtr    hPrinter = new IntPtr();
        DOCINFOA    di = new DOCINFOA();
        bool bSuccess = false; // Assume failure unless you specifically succeed.

      
        di.pDocName = "My C#.NET RAW Document";
        di.pDataType = "RAW";
       // di.pOutputFile = "";

        // Open the printer.

        if( OpenPrinter( szPrinterName.Normalize(), out hPrinter, IntPtr.Zero ) )
        {
            // Start a document.
            if( StartDocPrinter(hPrinter, 1, di) )
            {
                // Start a page.
                if( StartPagePrinter(hPrinter) )
                {

                    MessageBox.Show("????? ?? ????? ???? ???? ????? ?? ???? ????  ");

                    // Write your bytes.
                    bSuccess = WritePrinter(hPrinter, pBytes, dwCount, out dwWritten);

                    EndPagePrinter(hPrinter);
                }
                EndDocPrinter(hPrinter);
            }
            ClosePrinter(hPrinter);
        }
        // If you did not succeed, GetLastError may give more information
        // about why not.
        if( bSuccess == false )
        {
                dwError = Marshal.GetLastWin32Error();
        }
        return bSuccess;
    }

    public static bool SendFileToPrinter( string szPrinterName, string szFileName )
    {
        // Open the file.
        FileStream fs = new FileStream(szFileName, FileMode.Open);

        // Create a BinaryReader on the file.
        BinaryReader br = new BinaryReader(fs,Encoding.GetEncoding(864));
        // Dim an array of bytes big enough to hold the file's contents.
        Byte[] bytes = new Byte[fs.Length];
        bool bSuccess = false;
        // Your unmanaged pointer.
        IntPtr pUnmanagedBytes = new IntPtr(0);
        int nLength;

        nLength = Convert.ToInt32(fs.Length);
        // Read the contents of the file into the array.
        bytes = br.ReadBytes(nLength);
        // Allocate some unmanaged memory for those bytes.
        pUnmanagedBytes = Marshal.AllocCoTaskMem(nLength);
        // Copy the managed byte array into the unmanaged array.
        Marshal.Copy(bytes, 0, pUnmanagedBytes, nLength);
        // Send the unmanaged bytes to the printer.
        bSuccess = SendBytesToPrinter(szPrinterName, pUnmanagedBytes, nLength);
        // Free the unmanaged memory that you allocated earlier.
        Marshal.FreeCoTaskMem(pUnmanagedBytes);
        return bSuccess;
    }
    public static bool SendStringToPrinter( string szPrinterName, string szString )
    {

        MessageBox.Show("???? ");

        IntPtr pBytes;
        Int32 dwCount;
        // How many characters are in the string?
        dwCount = szString.Length;
        // Assume that the printer is expecting ANSI text, and then convert
        // the string to ANSI text.
        pBytes = Marshal.StringToCoTaskMemAnsi(szString);
        // Send the converted ANSI string to the printer.
        SendBytesToPrinter(szPrinterName, pBytes, dwCount);
        Marshal.FreeCoTaskMem(pBytes);
        return true;
    }
}